The invention relates generally to the field of non-human, transgenic animal models for human immunodeficiency virus (HIV), and more specifically to the production and methods of use of a rodent model for HIV.
Acquired Immune Deficiency Syndrome (AIDS) is a severe immunodeficiency disorder caused by infection with the human immunodeficiency virus (HIV). It is recognized that a major consequence of infection with HIV is the substantial loss of a class of T-cells commonly known as xe2x80x9chelperxe2x80x9d T-cells, which are the target cells for HIV infection. The entry of HIV into these and other target cells requires the interaction of the HIV virus with cell-surface CD4 molecules and a chemokine receptor, with different strains of HIV exhibiting both cellular and chemokine receptor specificity. (Speck et al., (1997) J. of Virol 71(9):7136-7139). Amino acids in the HIV env protein appear to determine the cellular tropism of an HIV strain as well as chemokine receptor preference (Speck et al., supra). For example, the chemokine receptor CCR5 mediates entry of HIV by macrophage-tropic strains (Deng, et al., Nature 381:661-666 (1996), whereas the chemokine receptor CXCR4 mediates viral entry for T cell line-tropic isolates (Feng, et al., Science 272:872-877 (1996)).
Transgenic rabbits expressing human CD4 have been generated in an effort to develop transgenic rabbit models of HIV disease.(Dunn, C. S., et al., J. Gen. Virol. 76 (Pt 6):1327-1336 (1995); Gillespie, F. P., et al., Mol. Cell Biol. 13:2952-2958 (1993); Leno, M. et al., Virology 213:450-454 (1995); U.S. Pat. No. 5,529,765). These studies demonstrated that transgenic rabbits expressing human CD4 were more susceptible to infection by HIV-1 than were their normal, non-transgenic counterparts. However, similar studies with transgenic mice expressing human CD4 showed that mouse cells are resistant to infection with HIV (Lores et al., (1992) AIDS Res. Hum. Retroviruses 8;2063). The reason for this difference in infectivity between the human CD4 transgenic rabbit model and the human CD4 transgenic mouse appears to be related to species-specific cofactors for post-entry viral processes.
Thus, there is a need for animal models within the HIV field that provide a more efficient, and cost-effective method of studying HIV infection in vivo. Rodent models are a more desirable model for HIV due to many characteristics such as size, reproductive cycle, cost of care, and the like. There is also a need in the HIV field for an animal model with a well characterized immune system.
The present invention features transgenic rodent animal models (e.g. rats, mice, and hamsters) for the study of HIV infection and replication, wherein the transgenic rodent is characterized by 1) expression of a human CD4 receptor and 2) expression of one or more human chemokine receptors. The transgenic animals may be either homozygous or heterozygous for these alterations. The bigenic or polygenic animals of the invention are further characterized by enhanced HIV infectivity and HIV replication within the cells of the transgenic rodent, both in vivo and in an in vitro culture of cells from these animals.
It is a general object of this invention to provide a transgenic rodent, in particular rodents belonging to a genus selected from Mus (e.g.xe2x80x94mice), Rattus (e.g.xe2x80x94Rat), and Mesocricetus (e.g.xe2x80x94hamsters), having stably integrated into its genome a human CD4 receptor and/or a human chemokine receptor, which transgenic rodent is susceptible to HIV infection.
In one aspect the invention features a method of screening for biologically active agents that modulate phenomena associated with HIV infection (e.g. immunosuppression, associated opportunistic infections, cancerous growths, etc), wherein the method involves the steps of combining a candidate agent with a transgenic rodent having 1) expression of a human CD4 receptor and 2) expression of a human chemokine receptor, and determining the effect of said agent upon a phenomenon associated with HIV infection. For example, the invention provides a method for using the animals of the invention in a screen for a vaccine that disrupts viral processes.
A primary object of this invention is to provide a transgenic rodent model for examining the effects of a candidate agent (e.g. a small molecule drug, endogenous factor, antiviral agent, etc.) on a phenomenon associated with HIV infection. Such transgenic animal models are useful for screening candidate agents for use in preventing, treating or relieving the symptoms of ARC and/or AIDS.
Another object is to provide a rodent model for HIV infection, thereby providing a useful means to study progression of infectivity and the associated syndromes, and in identifying means for preventing HIV infection.
It is yet another object of this invention to provide a transgenic rodent or transgenic rodent cell expressing the structural genes of HIV.
Yet another object is to provide a model for the assessment of infectivity and pathogenicity of a particular isolate of HIV.
In another aspect of the invention, the transgenic rodents of the invention are further manipulated to allow expression of a human gene that binds to a viral sequence, for example a gene encoding a protein that interacts with an HIV transactivation domain such as Tat. Preferably, this human gene is Cyclin T.
A feature of the invention is that transgenic rodents (e.g. mice and rats) of the invention have cells which express human CD4 receptor and a human chemokine receptor on their surface.
An advantage of the invention is that transgenic rodents or rodent cells (e.g. rats and mice) of the invention are infected and support viral replication upon inoculation with a variety of different strains of HIV.
These and other objects, advantages and features of the present invention will become apparent to those persons skilled in the art upon reading the details of the invention more fully set forth below.